/Engine/Source/Runtime/MovieScene/Public/EntitySystem/MovieSceneInstanceRegistry.h
This method will look up the hierarchy root from the given instance handle, and then look for the appropriate sub-instance with the given sequence ID.
[FInstanceHandle](API\Runtime\MovieScene\EntitySystem\FInstanceHandle) FindRelatedInstanceHandle ( [FInstanceHandle](API\Runtime\MovieScene\EntitySystem\FInstanceHandle) InstanceHandle, [FMovieSceneSequenceID](API\Runtime\MovieScene\FMovieSceneSequenceID) SequenceID ) const